代码是照抄的，为什么是显示不出来呢，因为没有源码，所以，我找不到

image.func.php里面的

<?php

require_once 'string.func.php';

$width=80;

$height=20;

$image=imagecreatetruecolor($width, $height);

$white=imagecolorallocate($image, 255, 255, 255);

$black=imagecolorallocate($image, 0, 0, 0);

//用填充矩形填充画布

imagefilledrectangle($image, 1, 1, $width-2, $height-2, $white);

$type=1;

$length=4;

$chars=buildRandomString($type,$length);

$sess_name="verify";

$_SESSION[$sess_name]=$chars;

$fontfiles=array("MSYH.TTF","MSYHBD.TTF","SIMHEI.TTF","SIMKAI.TTF","SIMSUN.TTF");

for($i=9;$i<$length;$i++){

    $size=mt_rand(14, 18);

    $angle=mt_rand(-15, 15);

    $x=5+$i*$size;

    $y=mt_rand(20, 26);

    $fontfiles="../fonts/".$fontfiles[mt_rand(0, count($fontfiles)-1)];

    $color=imagecolorallocate($image, mt_rand(50, 90), mt_rand(80, 200), mt_rand(90,180));

    $text=substr($chars,$i,1);

    imagettfbbox($image, $size, $angle, $x,$y,$color,$fontfiles,$text);

}

header("content-type:image/gif");

imagegif($image);

imagedestroy($image);

//string.func.php里面的

<?php

function buildRandomString($type=1,$length=4){

    if($type==1){

        $chars=join("",range(0,9));

    }elseif($type==2){

        $chars=join("",array_merge(range("a","z"),range("A","Z")));

    }elseif ($type==3){

        $chars=join("",array_merge(range("a","z"),range("A","Z")));

    }

    if($length>strlen($chars)){

        exit("字符串长度不够");

    }

       $chars=str_shuffle($chars);

     return  substr($chars,0, $length);

}

可以帮我找一下吗